The Doctor and Sarah Jane Smith return from their medieval adventure, but when they arrive in modern-day London, the streets are bare, the people are nowhere to be seen, and dinosaurs stalk the streets. Like everyone else, the Brigadier and UNIT have gone underground, hiding from the enormous reptiles while they try to figure out what suddenly brought them to the present day. The Doctor and Sarah soon discover that it’s the product of an illegal time experiment designed to restore Earth to simpler, less polluted, less corrupt times – and it has come about thanks to a startling betrayal by one of the Brigadier’s most trusted officers.
written by Malcolm Hulke
directed by Paddy Russell
music by Dudley SimpsonGuest Cast: Nicholas Courtney (Brigadier Lethbridge-Stewart), John Levene (Sergeant Benton), Richard Franklin (Captain Yates), Noel Johnson (Charles Grover), Peter Miles (Professor Whitaker), Martin Jarvis (Butler), Pat Gorman (UNIT Corporal), James Marcus (Peasant), Ben Aris (Shears), John Caesar (Soldier), Gordon Reid (Phillips), George Bryson (Ogden), Terry Walsh (Looter), John Bennett (General Finch), Martin Taylor (Corporal Norton), Dave Carter (Duffy), Terence Wilton (Mark), Brian Badcoe (Adam), Carmen Silvera (Ruth), Colin Bell (Bryson), Timothy Craven (Robinson), Trevor Lawrence (Lodge)
Broadcast from January 12 through February 16, 1974
LogBook entry & review by Earl Green
Review: Invasion Of The Dinosaurs is a difficult story for most fans to review. The first episode of this six-part story was simply titled Invasion, in an attempt to preserve the surprise of the story’s chief nemesis (this despite extensive advance promotion of the dinosaurs’ presence in such publications as the Radio Times). However, during a routine purge of 1960s B&W videotapes that the BBC felt would no longer be needed (I leave you to cringe at the impact this has had on the Doctor Who archives on your own time), part one of this story was erased along with all eight video master tapes of the 1968 Patrick 
Troughton/Cybermen story The Invasion. The only surviving copy of part one of Invasion Of The Dinosaurs is in B&W (a copy of a film print sold abroad to various eastern European and Middle Eastern countries), and it’s not in great shape.
Sad to say, you’re not missing much if you haven’t seen this one, complete or otherwise. The dinosaurs are only slightly more effective than the goofy guy-in-a-dinosaur-suit thunder lizards seen in Doctor Who And The Silurians. There are some interesting historical firsts, including the first appearance of the Jon Pertwee-commissioned, flying-saucer-shaped Whomobile car (never referred to by that name onscreen), and to be honest, there is something compelling surrounding the character development of UNIT turncoat Mike Yates – heck, that’s the most character development bestowed upon any member of UNIT until Battlefield came around in 1989. But the plot’s a bit muddled – the whole fake-spaceflight scam almost seems grafted on to extend the story by two episodes, but it was intriguing enough that it should’ve been developed into a separate story. It’s little wonder then that Invasion Of The Dinosaurs has been relegated to the dubious distinction of being the last full Doctor Who story ever to be commercially released on videotape by the BBC – complete with that hard-to-find first episode.